Since the invention of the two-wheeled motorized vehicle, various means have been sought to give greater stability to this type of vehicle when stationary. The vehicle's small overall dimensions offer major advantages in terms of driving in traffic and parking, and enhanced stability would make it possible to enclose the vehicle and provide it with the same level of comfort and safety as three- or four-wheeled vehicles.
Applicant's U.S. Pat. Nos. 4,921,263 and 4,974,863, represent the most recent state of the technique. Their basic principle is that the vehicle comprises two elements, chassis and body, the body being pivoted on the chassis in such a way that, whenever the whole vehicle departs from the apparent vertical due to gravitational and centrifugal forces, a link is created between the chassis and body causing the center of gravity of the body to rise relative to the chassis, which in turn raises the center of gravity of the whole vehicle. This movement consumes energy and is therefore clearly impossible unless some external contribution of energy exits which generates vehicle stability.